This invention relates to a valve actuating device for multiple valve type engines and more particularly to an improved valve operating arrangement for such engines.
It is generally acknowledged that the performance of an internal combustion engine can be improved significantly by utilizing multiple valves. The use of multiple valves for either or both of the intake and/or exhaust function has been found to permit a greater flow area with reduced reciprocating masses. For this reason, it is the common practice for many engines now to use four valves per cylinder (two intake and two exhaust). Even greater advantages can be enjoyed if more than four valves per cylinder are utilized. However, as the number of valves in the cylinder increases, there are other problems that arise which can reduce the power output of the engine. Specifically, as a greater number of valves are used, the configuration of the combustion chamber becomes more difficult to design. Specifically, as greater numbers of valves are employed, the combustion chamber surface area tends to increase and the compression volume also increases. These increases in surface area and compression volume can significantly reduce the power gains achieved by multiple valve engines.
An arrangement has been proposed wherein the use of multiple valves can be enjoyed without the aforenoted defects as to increased combustion chamber volume and surface areas. An arrangement as shown in U.S. Letters Pat. No. 4,624,222, entitled "Intake Valve Structure for Internal Combustion Engine", issued Nov. 25, 1986, and assigned to the assignee of this invention, employs at least three intake valves for a given combustion chamber without adversely affecting the combustion chamber volume or surface area. This is achieved by employing a different angle between the valves and the cylinder bore axis and also by shortening the length of some of the valves relative to other of the valves so as to permit these results. Although this arrangement has the advantages as aforenoted, it results in engines having different length valves serving the same purpose. This gives rise to certain problems in connection with stocking parts, assembly and servicing and reassembly. Furthermore, the use of longer valve stems increases the inertia of the reciprocating masses and this is, obviously, undesirable.
It is, therefore, a principal object of this invention to provide an improved valve actuating device for multiple valve type engines.
It is a further object of this invention to provide a valve arrangement for a multiple valve engine that permits the use of valves having different angles to the combustion chamber yet permits them to be operated by the same camshaft and have the same length.